The invention relates to a projected and secured virtual keyboard.
The invention more particularly relates to a method for inputting a text based on the positioning space of the fingers while referring to a projected image.
The European patent EP980039 describes a method for inputting characters through a virtual keyboard. A virtual keyboard is a means for inputting texts in the absence of a peripheral unit including one key per character and which is more particularly intended for equipment such as interactive television, cellular phones or personal terminals PDAs. Virtual keyboards can also be applied in the field of secured exchanges.
Patent PCT W09914657 is known in the state of the art and discloses a virtual keyboard used on a computer screen to emulate a conventional keyboard. The coordinates of the keys of the virtual keyboard are stored in a memory as a table, by the computer. The key coordinates are sorted in the table as a function of their occurring frequency. A pointing device makes it possible to select the keys on the virtual keyboard. The input points generated by the pointing device are compared one by one to the coordinates of the keys kept in the coordinates table. To decide whether the input point matches a considered key, defined criteria are applied to a terminal function. If they match, the key is affected to the input point and the search stops. The search for the matching key goes on until a match is detected or until the end of the table.
The American patent U.S. Pat. No. 5,008,847 discloses another type of virtual keyboard including a means of selection by a cursor moved on a graphic representation of a keyboard.
These prior art solutions have the drawback of having a fixed geometry and of being easily spied on within the scope of the inputting of secret information. In addition, the prior art solutions are particularly vulnerable in case of presence of an hostile module on the electronic device in charge of presenting the virtual keyboard.